2-trihalomethyl-1, 3-dioxolane-4-carboxybenzoate and carboxyalkanoate



Patented Mar. 18, 1952 UNITED STATES PATENT OFFICE 2-TRIHALOMETHYL-L3- DIOXOLANE- l- CAR- BOXYBENZOATE AND CARBOXYALKANO- ATE Elmer F. Schroeder, Chicago, 111., assignor to G. D. Scarlett? Co., Chicago, lll., a corporation of Illinois No Drawing. Application June 2, 1950, Serial No. 165,878

wherein X is a halogen and Y is an alkoxyl, nitrate, carboxybenzoate, or carboxyalkanoate group.

This application is a continuation-in-part of my copending application Serial No. 736,317, filed November: 15., I947, abandoned.

The substances to which this invention relates aregenerally useful as hypnotics and sedatives; They have theproperty of depressing the central nervous. system and arestherefore usef'ulin pharmaceutical preparations. Certain of the compoundsare effective both by parenteral and oral routes and others are active orally. Many of them are of value as disinfectants.

Compounds: of thisinvention are readily prepared by condensing a suitable a'fi-dihydroxy compound with chloral or bromal or hydrates thereof in the presence of dehydrating agents such as sulfuric acid orzinc chloride; During these-reactions-water is split out under the" influence of" the dehydrating agentand a heterocyclic 'dioxolane ring is formed; My compounds may alsobe prepared by treating a suitablysubstituteddioxolane such as one bearing in the 4-position' a hyd'roxymethyl'group with a nitrating or acylating agent, as for example nitric acid and aliphatic and aromatic dibasic acid halides and anhydrides.

In the general structural formula given hereinabove, X represents av halogen of atomic number greater than nine such as bromine or chlorine, Y represents a substituent such as alkoxyl, nitrate, carboxybenzcate or carboxyalkanoate. Among. the alkoxyl' groups which. my invention contemplatesare. the-lower. alkoxylj radicals such aslmethoxyl, ethoxylj. propoxyl',v iSDPI'DDOXYL. butoxyland the like. The terms."carboxyallianoate as-used herein and in the appended claims. means an aliphatic acid radical or alkanoate radical bearing a carboxy-l substituent. A carboxyalkanoate group can be represented by the formula HOOC--All --CO.Q wherein Alk is analkylene radicab The-bivalent radical; Alli, isfderiyed 8 Claims. (Cl. 26Q-3'38) from a saturated. aliphatic hydrocarbon by the removal of two hydrogen atoms. A carboxyalkanoate group is derived from a saturated aliphatic dibasic acid, anhydride. orv acid halide by reaction. with a hydroxyl radical, such as the hydroxyl. radical of a 4-hydroxymethyl1-Lit-dioxolane. A carboxybenzoate group is. represented by the formula HOOCC6H4.COO, wherein Cal-I4. represents a phenylene radical. It is derivedv from. a dibasicacid of the benzeneserieaor halide or anhydride thereof. The. free-carboxyl radical of the carboxya-lkanoate or carboiwbenzoategroup readily formssalts withorganic and inorganic bases and the dioxolane compounds carrying such substituents are thereby soluble in dilute aqueous bases, forming clear solutions which are nearly neutral and which are stable over long periods of time. Among the carboxyalkanoate radicals which are within the scope of this invention are those derived from dibasic aliphatic acids such as malonic, succini'c, glutaric; adipic and the like, as well as thosederived from similar alkyl-substituted aliphatic dicarboxylic acids such as methylsuccinic, dimethylsuccinic, methyladipic, ethyladipic and related acids. The carboxybenzoate radicals are'those derived from phthalic, terephthalic and isophthalic acids.

Salts of an acidic compound of the formula Hr-Q cn cxi (Era-o dnT-o-o OR-C 0 on wherein X is a halogen and R is an alkylene or phenylene radical, can be prepared in a purified state by solution of said acidic substance in an alcoholic solution of ]a base, followed by'precipitation of the desired salt. by the addition of' an other water-miscible solvent and adding an equivalent of an aqueous, orv alcoholic solution of a base and evaporatingthe. resulting solution toxdryness. preferably under reduced pressure.

Bases which are suitable for this purpose include ammonia, aliphatic amines, low-molecular weight heterocyclic amines, alkalies and the like. The salts of the foregoing acids are therefore suitable for parenteral administration in aqueous solution. The substances wherein Y represents alkoxy and nitrate radicals are generally soluble in fats and oils and can be administered orally in such solutions or dispersions.

The substances of this invention exist as a pair of cis-trans isomers, each being a racemic mixture of optical isomers. Therefore each of the products may be resolved into two geometric isomers, and the latter into four optically active isomers.

When 2 trichloromethyl 4 hydroxymethyl- 1,3-dioxolane is oxidized to 2-trichloromethyl- 1,3-dioxolane-4-carboxylic acid, two crystalline isomers are obtained (application of Elmer- F. Schroeder, Serial No. 4,930, filed January 28, 1948, now U. S. Patent 2,532,340, dated December 5, 1950). The lower-melting form of this 'acid (melting point 78-79 centigrade) loses hydrogen chloride readily on heating and is therefore considered to be the cis isomer. The higher-melting form (M. P. 133-134 C.) is taken as the trans form. The 2-trichloromethy1-4-hydroxymethyl- 1,3-dioxolane obtained by hydrolysis from the crystalline 2 trichloromethyl 1,3-dioXolane-4- carbinol acid succinate yields the higher-melting 2 trichloromethyl 1,3-dioxo1ane-4-carboxylic acid on oxidation with nitric acid, indicating that these compounds have the trans configuration.

The cis form can be represented as follows:

l C O/ \CX:

wherein X is halogen and Y is hydroxymethyl or carboxyl. The trans isomer can be shown as follows:

c--o \H Y/ The cis-trans isomers have diiferent physical properties and may be separated by means of their varying solubilities in organic solvents. The optical isomers have the same solubility properties and hence must be separated through their salts with optically active organic bases such as brucine and strychnine, as well as cinchonidine, cinchonine, hydroxyhydrindamine, menthylamine, morphine, a-phenylethylamine, phenyl oxynaphthyl methylamine, quinidine, quinine, and pseudo-ephedrine.

My invention is further disclosed by the following examples which are provided for the purpose of illustration and which are not intended in any way to limit this invention in spirit or in scope. The subject matter of Examples rand 2 is disclosed and claimed in my copending application, Serial No. 262,644, filed December 20, 1951.

Example 1 g. of 2-trichloromethyl-l-hydroxymethyl- 1,3-dioxolane, 20 cc. of concentrated nitric acid and 20 .cc. of water are mixed, warmed to about 60-65 C. and stirred until dissolved. The mixture is allowed to evaporate on a steam bath in anopen vesselfor 3 hours, then 60 cc. of water are added and the mixture is cooled. Crystals of 2 trichloromethyl 1,3-dioxolane-4-carbinol nitrate separate. These are removed by flltra tion and dried. After recrystallization from dilute alcohol the compound melts at 68-69 C. This compound has the formula (EHz-O-NO:

Example 2 70 g. of chloral hydrate are mixed with 225 cc. of concentrated sulfuric acid, stirred until liquefied, and cooled to 5 C. 40 g. of glycerol a-monoethylether are added at such a rate that the temperature remains between 5 and 15 C. with external chilling. After the addition, the reaction mixture is allowed to come slowly to room temperature with stirring. It is then poured on about 1200 g. of ice. The oily layer is separated and washed with water. It is taken up in chloroform, washed with water, dilute sodium carbonate, and again with water. The solution is dried and evaporated. The residue of 2-trichloromethyl-l-ethoxymethyl-1,3-dioxolane distills at 125-126 C. at 14 mm. pressure. This substance has the formula Example 3 400 g. of 2 trichloromethyl-4-hydroxymethyl- 1,3-dioxolane, 1000 cc. of pyridine and 200 g. of succinic anhydride are thoroughly mixed and heated to about C. for 3 hours. After standing overnight the mixture is diluted with parts of water. Most of the pyridine and water is removed under vacuum. One liter of water is added to the resulting syrup and a thick oil settles out. This is removed by decantation, and the oil is taken up in one liter of methylene chloride. This solution is washed with water, dried and evaporated under vacuum to remove solvent. 2- trichloromethyl 1,3 dioxolane-l-carbinol acid succinate so obtained is readily soluble in dilute sodium bicarbonate solution. An aqueous solution of the sodium salt is extracted with ether to remove organic materials and precipitated by the addition of an excess of 5 N hydrochloric acid. The succinate precipitates as a heavy syrup which can be purified by washing, by decantation and drying. This compound has the formula Example 4 A. 915 g. of the syrupy 2-trichloromethyl-1,3- dioxolane-l-carbinol acid succinate (Example 3). consisting of a mixture of cis and trans isomers, each a racemate, is dissolved in 915 cc. of hot toluene. To this are added 640 cc. of warm petroleum ether. The solution is cooled to room temperature. On scratching the side of the flask crystals of the trans isomer slowly separate. After the mixture has stood for about 3 days at room temperature, the crystals are collected on a filter and the filtrate, containing the cisisomer,

isretained (part B). Theyare washed with a mixture of toluene and petroleum ether; then with petroleum ether. The crystalline isomerzis recrystallized from a mixtureof 3 parts of toluene and 1 part of petroleum ether. The trans form of 2-trichloromethyl 1,3 dioxolane-i-carbinol acid succinate forms colorless needles of M. P. 85-87" C. The crystalsare only slightly soluble in water but dissolve readily in aqueous sodium bicarbonate solution, or'other alkaline solutions, with the formation of a solution of the soluble sodium salt...

B. The filtrate from the crystals of the trans isomer is evaporated under reduced pressure, yielding a. syrup consisting mainlyof. the cis isomer of 2-trichloromethyl 1,3. dioxolane-4.- carbinol acidsuccinate...

Example 5 225. g. of trans 2 trichloromethyll',,3'-dioxolane-4-carbinol acid. succinate. are suspended in 500 cc; of water and treated gradually with stirring with a cooled solution of '70 g. of sodium hydroxide in 500 cc. of water. The solid dissolves rapidly and an oil then begins to separate. After two hours at room temperature the oil is separated, dissolved in 300 cc. of methylene chloride and washed well with water. The solution is dried with anhydrous sodium sulfate and then evaporated under reduced pressure. The residue of trans 2 trichloromethy1-4-hydroxymethyl- 1,3-dioxolane distills at 103-104 C. at 1 mm. pressure.

Example 6 22 g. of trans 2 trichloromethyl-4-hydroxymethyl-1,3-dioxolane are dissolved in 50 cc. of anhydrous pyridine and treated with 14.8 g. of phthalic anhydride. The solution is heated for about two hours at 100 C., then cooled, treated with 5 cc. of water and finally distilled under reduced pressure to remove pyridine. The residue of trans 2 trichloromethyl-1,3-dioxolane-4- carbinol acid phthalate is taken up in chloroform. washed with dilute sulfuric acid and with water and dried over anhydrous sodium sulfate. The solvent .is removed by evaporation and the residue slowly crystallizes. After recrystallization from petroleum ether trans 2 trichloromethyl-l,3- dioxolanel-carbinol acid phthalate forms colorless crystals which melt at 93-95 C. This compound forms an insoluble salt with brucine, indi-- cating that resolution of the trans form into its two optical isomers is possible. The isomers could then be hydrolyzed back to the two optically active isomers of trans 2 trichloromethyl-4- hydroxymethyl-1,3-dioxolane. The latter could be esterified with succinic anhydride, forming two optically active isomers of trans-Z-trichloromethyl-1,3-dioxolane-4-carbinol acid succinate.

Example 7 10 g. of trans 2 trichloromethyl-1,3-dioxolane- 4-carbinol (Example 5) is covered with cc. of

concentrated nitric acid and warmed on a steam bath. After several minutes fumes of nitric oxide are evolved and a vigorous reaction sets in. The reaction mixture is removed from the steam bath and allowed to cool. in about five minutes. Heavy crystals of trans-2- trichloromethyl 1,3 dioxolane 4 carboxylic acid precipitate. The reaction mixture is evaporated nearly to dryness, Water being added from time to time until the nitric acid is expelled. The residue is taken up in dilute sodium bicarbonate solution, washed with methylene. chloride, boiled toqexpelptheorganic solvent; cooled-TandIacidified with concentrated hydrochloric acid. Crystal'swof. trans 2 trichloromethyl-1,3-dioxolane-4-carboxylic acid separate. These are removed, washed with water, and dried; They. melt at 134-135 C.

Example 8 solution of 273 g. of 2-tribromomethyl-4- .hydroxymethyl-1,3-dioxolane and 1100 g; of suc- 'cinic'anhydride in 500 cc; of pyridine is kept: atv

vv70-430" C. for three hours. It is left overnight at room temperature and then diluted with 50 cc. of water. Most of the water and pyridine is evaporated under vacuum. The resulting syrup is diluted with 500 cc. of water and the oily precipitate is removed by decantation and dissolved in 500 cc. of methylene chloride. The-resulting.

- {solution is..washe.d thoroughly with. water, dried -This is separated and dried. It has the formula CHq-O CH-CBra H0 Hz-()CO-CH7CH2CO0H I claim: 1. A 1,3-dioxolane ester of the structural formula our-o CH-CX;

11-0 JHz-Y wherein X is a halogen of atomic number greater than 9 and Y is a member of the group consisting of carboxybenzoate and carboxyalkanoate groups.

2. A 1,3-dioxolane ester formulaof the structural salts thereof.

3. A 1,3-di0xolane ester of the structural formula The reaction is complete 6 wherein Y is a carboxyalkanoate radical, and

salts thereof.

4. A 1,3-di0xolane ester of the structural formula car-o than 9, and salts thereof.

5. A 1,3-dioxolane ester of the structural formula CHg-O and salts thereof.

6. A 1,3-dioxolane ester of the structural formula and salts thereof.

: '1. 2 trichloromethyl 1,3 dioxolane 4 carbinol a oid succinate, which has the structural formula 11-0 errr-o-c d-CHzCHz-C o 011 8. 2 trlchloromethyl 1,3 dioxolane 4 carbinol acid phthalate, which has the structural formula CHz-O 5 l an-e01,

ELMER F. SCHROEDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,028,403 Mares Jan. 21, 1936 2,245,260 Dickey June 10, 1941 2,286,791 Dickey June 16, 1942 

1. A 1,3-DIOXOLANE ESTER OF THE STRUCTURAL FORMULA 